Novel peripherally tetra substituted metal-free,cobalt(II), copper(II) and manganese(III) phthalocyanines bearing polyethoxy chain attached by 2,6-diphenylphenol groups: synthesis,characterization and their electrochemical studies

Metal free (6), cobalt(II) (7), copper(II) (8) and manganese(III) (9) phthalocyanines, which are tetra substituted at the peripheral positions with 2-[2-(1,1′:3′,1′′-terphenyl-2′-yloxy)ethoxy]ethoxy groups, were synthesized and characterized by IR, ¹H-NMR,¹³C-NMR, UV–Vis and mass spectroscopy. Electrochemistry of the phthalocyanines were studied with voltammetric measurements by using cyclic voltammetry and square wave voltammetry techniques in DCM/TBAP electrolyte on a Pt working electrode. Electrochemical measurements exhibit that incorporation of redox active metal ions, Co^II and Mn^III, into the phthalocyanine core extends the redox capabilities of the Pc ring including the metal-based reduction couples of the metal. While Mn^IIIClPc showed only metal based reduction reactions, Co^IIPc showed metal based and ligand based reduction reactions as expected. Cyclic and square wave voltammetric studies showed that phthalocyanines have reversible/quasireversible/irreversible redox processes, which are the main requirement for the technological usage of these compounds.     

Analyzing the surface properties of acrylic-based water-soluble polymers

The surface properties of newly synthesized N-methoxy isopropyl acrylamide, N-methoxy isopropyl methacrylamide, cyclo propyl acrylamide, and cyclo propyl methacrylamide polymers were investigated using inverse gas chromatography. The highest dispersive component of the surface energy value was obtained for cyclo propyl methacrylamide at 30°C. The values obtained for all polymers were decreasing with the increasing temperature. The values obtained for the acidic and the basic parameters revealed strong basic characters for the surface of N-methoxy isopropyl methacrylamide and cyclo propyl methacrylamide polymers and weak basic characters for the surface of N-methoxy isopropyl acrylamide and cyclo propyl acrylamide polymers.     

The reaction of hexachlorocyclotriphosphazatriene with P-aminophenol

The reaction of hexachlorocyclotriphosphazatriene (1) with p-aminophenol (2) produced two new products: the open chain compound N₃P₃Cl₅(NHC₆H₄OH) (3), and the bridged compound N₃P₃Cl₅(NHC₆H₄O)N₃P₃Cl₅(4). The compounds 3 and 4 were separated and characterized by elemental analysis, massspectrometry and NMR spectroscopy. The molecular structures of compounds 3 and 4 were determined by X-ray crystallography. Compound 3 is the first example of cyclotriphosphazene including (p-hydroxyphenyl) amino group and compound 4 was the first example of the N-substituted p-aminophenoxy group with cyclotriphosphazene.     

Complete mappings and Carlitz rank

The well-known Chowla and Zassenhaus conjecture, proven by Cohen in 1990, states that for any \(d\ge 2\) and any prime \(p>(d^2-3d+4)^2\) there is no complete mapping polynomial in \(\mathbb {F}_p[x]\) of degree d. For arbitrary finite fields \(\mathbb {F}_q\), we give a similar result in terms of the Carlitz rank of a permutation polynomial rather than its degree. We prove that if \(n<\lfloor q/2\rfloor \), then there is no complete mapping in \(\mathbb {F}_q[x]\) of Carlitz rank n of small linearity. We also determine how far permutation polynomials f of Carlitz rank \(n<\lfloor q/2\rfloor \) are from being complete, by studying value sets of \(f+x.\) We provide examples of complete mappings if \(n=\lfloor q/2\rfloor \), which shows that the above bound cannot be improved in general.     

The effect of the double bond pyramidalization on the mode of the bromination reaction: bromination of benzobicyclononadiene

The bromination of 6,7,8,9-tetrahydro-5H-5,9-ethenobenzo[a][7]annulene yielded regio- and stereospecifically formed dibromides arising from the alkyl shift where the bromine exclusively attacks the double bond from the endo face of the double bond. DFT calculations on model compounds showed that the pyramidalization of the double bond and steric repulsion caused by the methylene protons are responsible for the stereo- and regioselective addition of bromine.     

Micellar effect on the sensitivity of spectrophotometric Mo(VI) determination based on the formation of gallic acid complex providing evidence for the polyoxoanion structure of molybdate ions

In this study effects of anionic (sodium dodecyl sulfate, SDS), cationic (cetyltrimethylammonium bromide, CTAB) and nonionic (Triton X-100, TX100) micelles on the sensitivity of spectrophotometric molybdenum(VI) (Mo) determination based on the formation of a binary complex with gallic acid (GA) were investigated.

Micellar CTAB was found to enhance the formation of Mo–GA complex. SDS micelles exerted an inhibitory effect while TX100 micelles had no effect on the complex formation. By the optimization of experimental conditions, the determination limit of the method suggested in the literature was lowered from 5.2 × 10⁻⁵ to 4.6 × 10⁻⁶ and to 5.7 × 10⁻⁷ M, in the absence and presence of CTAB, respectively.

The mechanism of the effect of CTAB was investigated by spectrophotometric titrations and it was concluded that CTAB did not form a ternary complex with Mo and GA. The stoichiometry of the complex, deduced from the results of spectrophotometric titrations, provided evidence for the formation of para-Mo₇O₄⁶⁻ polyanions at pH 4.5, indicating to the formation of a charge transfer complex between these ions and GA in micellar medium.     

Spectrophotometric determination of ascorbic acid by the modified CUPRAC method with extractive separation of flavonoids-La(III) complexes

The proposed method for ascorbic acid: AA (Vitamin C) determination is based on the oxidation of AA to dehydroascorbic acid with the CUPRAC reagent of total antioxidant capacity assay, i.e., Cu(II)-neocuproine (Nc), in ammonium acetate-containing medium at pH 7, where the absorbance of the formed bis(Nc)-copper(I) chelate is measured at 450 nm. The flavonoids (essentially flavones and flavonols) normally interfering with the CUPRAC procedure were separated with preliminary extraction as their La(III) chelates into ethylacetate (EtAc). The Cu(I)-Nc chelate responsible for color development was formed immediately with AA oxidation. Beer's law was obeyed between 8.0 × 10⁻⁶ and 8.0 × 10⁻⁵ M concentration range, with the equation of the linear calibration curve: A_450 nm = 1.60 × 10⁴C (mol dm⁻³) − 0.0596. The relative standard deviation (R.S.D.) in the analysis of N = 45 synthetic mixtures containing 1.25 × 10⁻² mM AA with flavonoids was 5.3%. The Cu(II)-Nc reagent is a lower redox-potential and therefore more selective oxidant than the Fe(III)-1,10-phenanthroline reagent conventionally used for the same assay. This feature makes the proposed method superior for real samples such as fruit juices containing weak reductants such as citrate, oxalate and tartarate that may otherwise produce positive errors in the Fe(III)-phen method when equilibrium is achieved. The developed method was applied to some commercial fruit juices and pharmaceutical preparations containing Vitamin C + bioflavonoids. The findings of the developed method for fruit juices and pharmaceuticals were statistically alike with those of HPLC. The proposed spectrophotometric method was practical, low-cost, rapid, and could reliably assay AA in the presence of flavonoids without enzymatic procedures open to interferences by enzyme inhibitors.     

Low temperature synthesis and characterization of Mn3O4 nanoparticles

Heating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn₃O₄ nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements confirm a typical Mn²⁺signal with a highly resolved hyperfine structure.